1. Field of the Invention
This invention relates to apparatus for detecting, characterizing and evaluating electromagnetic radiation, primarily in the radio frequency (RF) range, which is emitted by the fusing portion of the explosive train found in certain destructive devices. The apparatus includes a system for containing cargo, such as airline luggage, in a sealed or confined environment shielded from outside radiation and subjecting any fusing devices, which may be located in such cargo, to the condition or conditions under which such devices are activated. The invention further includes equipment for detecting any electrical signals emitted by such fusing devices.
2. Description of the Prior Art
The introduction of explosive devices into aircraft and transportation vehicles through passenger luggage is a danger heightened by recent events. The presence of such devices endangers the lives of passengers on board aircraft or other vehicles and, on occasion, has resulted in loss of life. Numerous attempts have been made in the prior art to prevent the introduction of such devices into public conveyances. Specially-trained animals have been used to identify the presence of explosives and have, in some cases, been successful in preventing explosive devices from being placed on board aircraft. Specially-designed explosive detectors are commercially available and have been proposed for use in aircraft and in luggage-handling areas. One such proposal is found in U.S. Pat. No. 4,866,439 issued Sept. 12, 1989 to John H. Kraus, which discloses an explosive detection system for commercial aircraft. The Kraus patent proposes the incorporation of detectors in the air ducting of the aircraft itself. Kraus notes that the use of such detectors in luggage areas has proved difficult because of the inherent time delay in the operation of explosive detectors of the type which he proposes to use. Such explosive detectors sense the presence of explosives through detection of odor or other airborne indicia of the presence of explosive material. The significant delay in the detection capability of such device has made them impractical in most applications.
Other techniques include the purposeful detonation of explosives in luggage. One such technique is disclosed in U.S. Pat. No. 3,075,461 issued Jan. 23, 1963 to Irwin Ehlmann. The Ehlmann patent discloses the use of a sweep frequency transmitter designed to detonate RF-sensitive blasting caps. The Ehlmann device is impractical because detonation of the cap causes a dangerous explosion. Also the luggage is always needlessly destroyed when this technique is used. The Ehlmann device is only effective when the detonator is sensitive to a specific frequency. Others have proposed the construction of explosion chambers for pressurizing or creating a partial vacuum in a confined area to test the explosive capability of devices. One such chamber is disclosed in U.S. Pat. No. 2,917,927 issued Dec. 22, 1959 to George F. Clark. Such chambers are of little value in detecting explosive devices because, although a pressure change may activate the device, the prior art has shown no way in which such device, once activated, could be detected.
The detection of a pressure sensitive device which initiates the electronic timer for an explosive device is an important problem which has not been properly addressed in the prior act. By the use of such devices in airline luggage, a terrorist can ensure that an aircraft is well into flight or over the ocean before any explosive device is activated. The present invention addresses this problem among others.